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Ctenophores are marine animals that possess eight rows of cilia that they use in locomotion.
Light scatters off these rows of cilia, often causing a "rainbow-effect" to radiate from ctenophores.
Although this phenomena is not actually bioluminesence, most ctenophores are bioluminescent
in addition to emitting the rainbow of light.
Ctenophores are carnivores that feed mostly on zooplankton,
with a few larger species feeding on invertebrate larvae and small crustaceans.
They use tentacles with specialized sticky cells to capture their prey and bring it to the mouth.
It is in this manner that ctenophores are capable of wiping out entire
ecosystems because of their carnivorous ways.
As voracious predators, ctenophores are capable of overpopulating ecosystems,
ravaging the food supply, and thus wiping out indigenous species of the area.
All ctenophores are hermaphroditic, releasing both eggs and sperm into the water as they swim.
The sperm find the eggs in the water, and fertilization then takes place.

Introduction to Ctenophora

Ctenophores (Greek for "comb-bearers") have eight "comb rows" of fused
cilia
arranged along the sides of the animal, clearly visible along the red lines in these pictures. These cilia beat synchronously and propel ctenophores through the water. Some species move with a flapping motion of their lobes or undulations of the body. Many ctenophores have two long tentacles, but some lack tentacles completely.

Ctenophores, variously known as comb jellies, sea gooseberries, sea walnuts, or Venus's girdles, are voracious predators. Unlike
cnidarians
, with which they share several superficial similarities, they lack stinging cells. Instead, in order to capture prey, ctenophores possess sticky cells called colloblasts. In a few species, special cilia in the mouth are used for biting gelatinous prey.

The phylogenetic position of ctenophores has been, and still is, in dispute. Ctenophores have a pair of anal pores, which have sometimes been interpreted as homologous with the anus of bilaterian animals (worms, humans, snails, fish, etc.). Furthermore, they possess a third tissue layer between the endoderm and ectoderm, another characteristic reminiscent of the Bilateria. However, molecular data has contradicted this view, although only weakly. Therefore, this is an active area of research.

Although most ctenophores swim, one group creeps along the bottom of the seas. Most of these species live on other animals, for instance with
echinoderms
,
sponges
, or benthic
cnidarians
. Many ctenophores, like various other planktonic organisms, are
bioluminescent
, able to give off light.

Until fairly recently, no fossil ctenophores were known. Like most pelagic cnidarians, the bodies of ctenophores are made up mostly of water, and the chances of leaving a recognizable fossil are very slim. Two species of fossil ctenophore have now been found in the Late
Devonian
, in the famous Hunsrückscheifer slates of southern Germany (Stanley and Stürmer, 1983, 1987). Both owe their preservation to rapid precipitation of pyrite in the tissues, and both are quite similar to living ctenophores in the order Cydippida (the "sea gooseberries.") Other ctenophore-like forms have been found in the
Cambrian
-age
Burgess Shale
of the Canadian Rocky Mountains and Chengjiang Formation of Southern China. These forms differ from living ctenophores in several ways, thus obscuring their phylogenetic affinities.

Little is currently known about the basic biology of most ctenophores; indeed, the individual in these pictures has not even yet been formally described and named, despite being large, spectacularly colored, and common. These photographs were made available to the
UCMP
by
Underwater World
, Queensland, Australia.